High strength fiber glass-metal construction and process for its manufacture



Feb. 10, 1959 K. s. SKAAR 2,872,865

HIGH STRENGTH FIBER GLASS-METAL CONSTRUCTION AND PROCESS FOR ITSMANUFACTURE Filed Sept. 29. 1955 2 Sheets-Sheet l & 2| 6 l6 2 3 \k R w?llllhlmlml INVENTOR. KARSTEN s. SK'AAR Feb. 10, 1959 K. s. sKAAR 2,

HIGH STRENGTH FIBER GLASS-METAL CONSTRUCTION AND PROCESS FOR ITSMANUFACTURE Filed Sept. 29. 1955 2 Sheets-Sheet 2 INVENTOR. KARSTEN' S.SKAAR ATTORNEY-S United States Patent HIGH STRENGTH FIBER GLASS-METALCON- STRUCTION AND PROCESS FOR ITS MAN- UFACTURE Application September29, 1955, Serial No. 537,593

9 Claims. (Cl. 102-56) (Granted under Title 35, U. S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royalties thereon or therefor.

This invention relates to improvements in high strength fiber-metalconstructions and methods for their manufracture and more specificallyto high strength joints between woven fiber-glass and-metal and tomethods for effecting such joints.

With the advent of fibers made from plastic materials and thedevelopment of high strength plastics, numerous efforts have been madeto develop plastic-metal combination constructions for various purposes.Obviously, for many applications, where great strengthandresistance toseparation are not necessary, such joints present only minor problems.However, in certain specific applications, as for example in effectingthe joints between metallic and plastic parts in rocket or warheadconstructions, the development of joints of sufiicient strength towithstand impact and the stresses set up in the firing of a missile havepresented extremely difficult problems. Prior tothe instant invention,no entirely satisfactory Patented Feb. 10, 1959 been discovered thatwhere woven fiber glass is used for the sleeving with any of a varietyof known plastic materials, a construction of adequate strength for useas a warhead may be achieved.

It is, therefore, an object of this invention to provide new highstrength tubular articles comprising plastic main bodies and includinghigh strength joints with metallic end members, and to provide methodsfor the manufacture of such articles.

Another object of this invention is to provide high strength warheadconstructions comprising plastic tubular bodies and metallic endmembers, the joint between the plastic. and metallic members being of ahigh order of strength, and to provide methods for the manufacture ofsuch warheads.

A still further object of this invention is to provide a technique forjoining pre-fabricated woven plastic material to metallic end members byutilizing such material in the form of sleeving and by providing meanseffecting solution has been achieved, particularly in the case ofwarhead constructions.

The development of a joint strong enough to withstand penetration of anobject, as for example steel plate,

without pulling apart is of extreme importance. The suc cessfuldevelopment of such a joint makes possible the construction of warheadsof adequate strength and less weight than prior art warheads utilizingmetallic casings. Thus, the performance characteristics of the conveyingmissiles can be improved by the resultant decrease of weight or by theinclusion of a larger quantity by weight of explosive than could be.carried by equivalent prior art missiles.

This invention is based upon the discovery that woven fibrous sleevingmay be used to form a shaped casing and to effect a strong joint with ametallic end member. If a length of such sleeving is turned back uponitself over a metal ring member, the ring member and the resultingdouble thickness of sleeving form a thickened reinforced end which maybe tightly joined toa metallic end member as by turning in one or bothof the lips of a prepared groove in the end member to clamp thereinforced end. Alternately, such a covered ring, member may be clampedbetween screw threadedly connected inner and outer metallic pieces toeffect a strong and tight joint. If such sleeving is impregnated with anappropriate hinder or plastic material-(either before or after effectingthe joint) and is cured after joining to the metallic structure in amanner appropriate to the nature of the binder or plastic used,theresulting structure is a rigid tubularabody having a tightlyconnected metallic end piece. In the foregoing manner, by appropnateclamping cooperation of such sleeving with a metallic end member toprovide a joint of a high order of strength.

Another object of this invention is to provide high strength tubulararticles made of plastic impregnated fiber glass having high strengthjoints with metallic end members and to provide methods for making sucharticles out of pre-fabricated woven sleeving to facilitate manufacturethereof.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein: a

Fig. 1 is a vertical sectional view of the nose portion of a tubularcasing according to this invention, illustrating the joint between theplastic tubing and the metallic nose structure; 1

Fig. 2 is afragmeutary vertical section of a modified form ofconstruction according to the invention; and

Fig. 3 is a vertical sectional view of a modified inner flange memberwhich may be used in place of the equivalent inner flange member shownin the modification of Fig. 1;

Figs. 4 to 9 are schematic showings of the steps of a method of forminga rigid tubular body of woven fabric and having a metallic'end member,according to this invention, Fig. 4 showing an elevation of a mandril onwhich the parts are assembled; Fig. 5 showing the mandril with the innerflange positioned thereon and a sleeve of woven fabric pulled thereover,the flange and fabric being shown in section; Fig. 6 being a viewsimilar to Fig. 5 showing the end ring member'in position; Fig. 7 beinga view similar to Fig. 6 showing the extended edge of the sleevingturned back over the ring;' Fig. 8 showing the final assembly, with 'theouter ogive member screw-threadedly engaging the inner flange tosecurely clamp the end ring and doubled sleeving in position;

' and Fig. 9 showing the assembly of Fig. 8 with the selection of hinderor plastic material, and by appropriate selection of woven or fibroussleeving, high strength tubular bodies having extremely strong JOIDtSwith metallic end members maybe formed and 1t has sleeving impregnatedwith a' suitable binder and positioned in a mold for curing.

Referring now to the drawings, in which like reference numerals are usedto designate like parts throughout, tubular structures according to thisinvention are illus'- trated in Figs. 1 and 2 and comprise rigid tubularmembers generally designated as T, and having end portions of enlargedcross-section, as at R, by which a tight joint may be effected withmetallic ogival nose pieces, generally designated as N. The rigidtubular members are laminar in construction, the laminae 2, 4 beingformed by bending one or more cylindrical sleeves back upon themselvesover a metallic ring member 6 to form the enlarged cross-section R.

The joint between the tubular members and the ogival or plastic nosepiece may be efiected in a variety of ways. In the particular jointshown in Fig. 1, 8 is an inner flange member in the form of an annulushaving a narrowed, cylindrical forward portion 10, and an outwardlyflared rearward portion 12. The forward portion 16 is screwthreadedexternally as at 11 for substantially its entire length and is smoothexternally for a portion of its length at the point of juncture with theflared portion 12, as shown at 14, to provide a bearing for the innerdiameter of the enlarged portion R of the tubular her. The outer surface16 of the inner flange member is bowed outwardly, as shown, to :providesurfaces to resist longitudinal relative movement of the parts when thejoint is completed. For cooperation with inner flange 8 in clampingenlarged portion R to hold the tubular member T in position, there isprovided an ogival outer clamping piece 18, which is in the form of anannulus. Outer piece 18 has an inner screw thread 19 for cooperationwith the external screw threads 11 of inner flange 8. At the rearwardend of outer piece 18 the thickness of the wall of the annulusdiminishes abruptly, to form a shoulder 20, the outer end ofthe shoulderterminating in a curved surface 21 of a radius to grip enlarged portionR. The annulus extends rearwardly into a continually diminishing skirt22 having a curved inner surface 24 of such configuration as tocooperate with the surface .16 of the inner flange member to clampinglygrip the side walls 2, 4 .of the tubular member T, the enlarged endportion R of the tubular member being clamped between the shoulder 20and the surface 21 of end piece 18, the smooth wall 14 of inner flangemember 8 and the forward cooperating portions of curved walls 16 and 24.

Fig. 3 illustrates a second form of inner flange member 12 which may beused to replace the inner flange member 12 as shown in Fig. 1 where lessclamping area along tubular member T is required. Member 12' performsprecisely the same functions as the member 12 in cooperating with thenose piece 18, clamping the enlarged portion R between the surfaces 14'and 16 of the inner flange member 8, and surfaces 20, 21 of the outerpiece 18.

Fig. 2 is illustrative of another modification of the present invention,in which the ogival nose structure is of one piece, the clamping of theenlarged portion R being effected by deformation of the metal of theside walls of a previously prepared groove. Thus, the nose piececomprises a single piece of metal having lips 26, 28 extendingrearwardly from a groove 30 of a size to receive enlarged portion R, thelip portions being formed with arcuate surfaces 32, 34 corresponding tothe surfaces 16 and 24 of Fig. l, to clamp the tubular member T and toresist longitudinal separation after completion of the assembly. Thestructure as shown in Fig. 3 is made by forming nose-piece N with thelips 26, 28 spread apart to form a groove for insertion of the tubularmember therein and one or both of the lips are then turned in to gripthe tubular member as shown.

In effecting the plastic-metal joints discussed hereinabove to form theillustrated tubular structures, the tubular member T may be any rigidplastic material of proper size and shape, having an enlarged endportion R. However, as explained hereinabove, this invention isparticularly concerned with the employment of impregnated woven fabricsuch as fiber glass fabric or fiber glass fabric modified by theinclusion of other materials as asbestos fiber, for example. When suchmaterials are used in the manner previously discussed, i. e., asflexible sleeving bent back upon itself over an end ring to form anenlarged end and a laminar wall structure, the joint with the metallicparts may be formed either before or after impregnation of the fabricwith the plastic material Thus, the end ring-sleeving assembly mayeither be olned to the nose piece as in Fig. 1 or Fig. 2 while stillflexible in form and subsequently impregnated 'with t binder .of plasticand cured, or said assembly may be formed and hardened and thenassembled with the nose piece. Furthermore, the wall thickness andnumber of laminations in such tubular members may be varied by selectionof the nature of the sleeving and the number of thicknesses thereofemployed.

As previously indicated, the binder or plastic employed to give strengthto the sleeving may be any one of a Wide variety of plastics. Thus, forexample, any of the known epoxy resins, polyester resins or phenolicresins may be used as the plastic material, and suitable catalysts maybe intermixed therewith when necessary or desired, to assistpolymerization and cross-linking of the plastic compound. Examples ofsuch catalysts are benzoyl peroxide (for use with the polyester resins);metaphenylene diamine, 4,4 methylene dianiline and boron trifluoridemonoethylamine complex (all for use with epoxy resins; and hexamethylenetetramine (for use with phenolic resins). The specific nature of thehinder or plastic material and/or catalyst is not of the essence of thisinvention, a wide variety of such materials being known to haveproperties obviously suitable to the purposes of this invention.

The methods of manufacturing articles as described above may be varied.Thus, a pre-stiffened tubular member may be clamped between screwthreaded nose piece elements 8 and 18 as in Fig. 1.; between the lips26, 28 of the nose piece of Fig. 2; or between elements 18 and 8' if theinner flange of Fig. 3 is used. Such a tubular member may be formed of aplastic as by molding; by impregnation and molding of plural laminarconstructions of filter glass materials in which, if desired, thedirection of the fibers of alternate layers may be arranged in aprescribed fashion; or if the woven sleeving which is the specificillustration of this disclosure is used, a length of sleeving may bepulled over a mandril for a portion of its length, the remainder beingpulled through a metallic ring member (see Fig. 6), and then turned backon itself (Fig. 7). Impregnation of the sleeving with a desired plasticmaterial may be either before or after the bending of the sleeving backupon itself as by wiping the plastic on. The assembly is then heatcurved in a mold to give it its final rigid shape. Impregnation may alsobe effected by placing the unimpregnated sleeving and ring assembly intoa mold, pouring the plastic into the mold and then curing the assembly.

Alternatively, assembly may be effected by directiy connecting theflexible sleeving to the nose-piece prior to impregnation or stiffeningthereof, and an illustrative example of onesuch procedure is depictedmore or less schematically in Figs. 4 through 9. In this process, anappropriately shaped mandril M, as shown in Fig. 4, is utilized. Aninner flange member 8 is positioned over the properly shaped end of themandril. As shown in Fig. 5, after member 8 is in place, a length ofwoven flexible sleeving is pulled over the mandril, the sleeving beingof such a length that upon bending back of the tubing about referenceline a--a of Fig. 5 a tubing of at least a length and thickness desiredwill be obtained. Thus, if plural plies for the full length are desiredthe tubmg must be at least twice the desired length, but the lengthcould be less if a partially single-ply structure were desired.Reference line a-a is located to indicate the ultimate position of theenlarged portion R, about section 14 of the inner flange 8 as shown inFig. 1.

After the sleeving is positioned about the mandril and inner flangeassembly as described in the preceding paragraph and shown in Fig. 5,the metallic ring member 6 1s positioned by pulling it over the free endof the sleeving to form the assembly shown in Fig. 6. Then the sleevingis bent back upon itself over ring member a to form a two-ply tubularstructure comprising the inner ply 2 and the outer ply 4 formed by thefree end, and having the enlarged portion R as shown in Fig. 7

The assembly is completed by screwing the outer piece 18 onto the innerflange member, cooperating screw threads 11 and 19 causing the pieces 8and 18 to be tightly connected and to clamp the tubing assembly as shownin Fig. 8 (and in Fig. 1). In this procedure, the sleeving may beimpregnated with the desired plastic material by vacuum techniques orother known techniques such as by being wiped into the sleeving, in itsposition over the mandril, as shown in Figs. 6 or 7. The impregnatedassembly, after connection with outer piece 18 may then be placed in amold 50 (preferably two-piece) for heat curing and shaping.Alternatively, the assembly of Fig. 8, unimpregnated, may be placed inthe mold and plastic material allowed to flow into the space occupied bythe woven fabric material. After saturation, the mold is placed in anoven for an appropriate time at a temperature proper for curing theparticular material used.

From the above it should be obvious that this invention provides new andimproved tubular constructions characterized by great strength and byimproved strength in plastic-metallic joints forming a part thereof.Moreover, this invention provides novel methods for the manufacture ofsuch constructions.

Obviously, many modifications and variations of the constructions andprocesses forming the present invention are possible in the light of theabove teachings. It is therefore to be understood that the. illustrativeexamples given are not intended to be limiting in nature, the scope ofthe invention rather being defined and described in the appended claims:

What is claimed is:

1. A tubular construction comprising a tubular main body formed oforiginally flexible fabric sleeving folded back upon itself to form aplurality of plies joined by a fold, a reinforcing ring memberpositioned between said plies at the fold to form a thickened end, arigid tubular end structure, said end structure having means toclampingly engage said thickened end to join said main body and said endstructure to form a unitary tubular construction, said flexible fabricbeing impregnated with shape retaining plastic material for giving saidimpregnated fabric a high order of rigidity and strength, said rigidtubular end structure comprising an inner flange member and an outerclamping piece, said inner flange member having a skirt portion tosupport the walls of said main body member adjacent the thickened endthereof and having an externally screw threaded portion extendingoutwardly through said thickened end, said outer clamping piece havingan internally screw threaded portion for cooperation with the externalthreads on said inner flange member, an outwardly directed shoulder atthe rearward end of said threaded portion and a rearwardly directedskirt portion complementary to that of the inner flange whereby thethickened end of said main body may be clamped between said shoulder andthe cooperating adjacent forward ends of said two skirt pornuns, and themain body wall adjacent said thickened end may be clamped between saidtwo skirt portions when said inner flange member and said outer clampingpiece are screw threadedly engaged with one another.

2. The tubular construction of claim 1 wherein said two complementaryskirt portions are outwardly flared whereby longitudinal forces tendingto separate the main body from the end structure are resisted.

3. The tubular construction of claim 2 further characterized in that theflexible fabric is a woven fabric containing glass fibers and isimpregnated with a shape retainmg plastic material whereby it has a highorder of rigidity and strength.

4. The method of manufacturing a composite tubular body which comprisesthe steps of pulling a portion of a length of normally flexible fabricsleeving through an end ring member and folding said length of sleevingback upon itself to form a tubular main section having a muIti-ply walland a thickened end, afl'ixing an end structure about said thickened endand about the adjacent niulti-ply wall of said main section, andimpregnating said fabric with a plastic binder material to impartstrength and rigidity thereto.

5. The method of claim 4 wherein said plastic binder material is anincompletely polymerized and incompletely cross-linked binder materialand wherein the assembled composite tubular body is then cured tocomplete polymerization and cross-linking of the binder material toproduce a strong and rigid structure.

6. The method of claim 5 wherein the fabric is of woven materialincluding fiber glass.

7. The method of claim 5 wherein said end structure comprises a unitarytubular construction having a pair of outwardly flared spaced integrallips extending longitudinally thereof to form a groove, said clampingbeing effected by pressing said lips together to clamp said thickenedend and multi-ply wall.

8. The method of manufacturing a cylindrical com posite fiberglass-metal cylindrical body which comprises rolling a cylindrical openended fiber glass sleeve of the required diameter back on itself with aring enclosed at the fold between the two cylindrical plies formed,aflixing the enclosed ring internally of a cylindrical metal part nearthe end of the metal part to be joined to the fiber glass sleeve,impregnating said fiber glass sleeve with a plastic binder, forming saidsleeve to the desired shape in a mold and curing said binder.

9. The method of manufacturing a composite tubular body comprising thesteps of providing an inner flange member having a rearwardly extendingoutwardly flared skirt and a forwardly extending externallyscrew-threaded portion, positioning a mandril having a reduced forwardend into said skirt portion to support the flange member on said forwardend of the mandril, placing a tubular woven fabric sleeving of lengthgreater than the mandril over the mandril and inner flange member with aportion of the sleeving extending forwardly of the inner flange member,pulling a ring member over said forwardly extending portion of thesleeving and positioning said ring member about said sleeving in theplane of the line of connection of the flared skirt of said inner flangeto the forward portion thereof, folding back said forwardly extendingportion of said sleeving upon the remainder of the sleeving on themandril to form a multi-ply tubular wall, screwing a complementarilyshaped outer clamping piece down onto said inner flange to clamp thesleeving and ring assembly between said inner flange member and saidclamping piece, placing the assembly in a mold, flowing thermosettingplastic material into the mold to fill the interstices of the fabricsleeving with said plastic material, and curing the thus impregnatedassembly to solidify the assembly to form a rigid, strong compositetubular structure.

References Cited in the file of this patent UNITED STATES PATENTS1,974,383 Wallace Sept. 18, 1934 2,099,915 Weatherhead Nov. 23, 19372,146,218 Kimmich Feb. 7, 1939 2,146,756 Miller Feb. 14, 1939 2,241,355Machlachlan May 6, 1941 2,359,952 Welger Oct. 10, 1944 2,368,911 AndlerFeb. 6, 1945 2,408,960 Stivason Oct. 6, 1946 2,500,117 Chandler Mar. 7,1950 2,612,925 Starr Oct. 7, 1952 2,653,887 Slayter Sept. 29, 19532,681,619 Chandler June 22, 1954 2,685,458 Shaw Aug. 3, 1954 2,741,496Melsom Apr. 10, 1956 FOREIGN PATENTS 402,535 Great Britain Dec. 7, 19331,098,880 France Mar. 9, 1955

